1

ELECTROMAGNETIC ENGINEERING ANNUAL REPORT 2006

CONTENTS Highlights 1 General resources

1.1 Personnel 1.2 Economy 1.3 Office facilities and laboratories

2 Undergraduate and continuing education

2.1 Undergraduate courses 2.2 Undergraduate theses 2.3 Continuing education

3 Graduate education

3.1 Graduate courses 3.2 Graduate theses

4 Research activities

4.1 Electromagnetic theory 4.2 Novel electromagnetic metamaterials 4.3 Electrotechnical modeling 4.4 Antenna theory and design 4.5 Insulation diagnostics 4.6 Reliability centered asset management (RCAM)

5 Publications and reports

5.1 Ph.D. theses 5.2 Licentiate theses 5.3 Master theses 5.4 Books 5.5 Articles in journals 5.6 Conference proceedings 5.7 Reports 5.8 Miscellaneous

6 Conferences, courses and visits

2

7 Seminars and lectures 7.1 Seminars and lectures at KTH 7.2 Seminars given outside KTH

8 Other activities 8.1 National assignments 8.2 International assignments 8.3 Mobility

3

Highlights The scientific and technical activities of Electromagnetic Engineering include basic electromagnetic theory and the physical and technical fundamentals for design of electrical devices. 2006 was the first year of the new division, Electromagnetic engineering, formed by merging the previous divisions Electromagnetic theory and Electrotechnical design. A brief summary of the most important events during 2006 is given below

o Three Ph.D. theses were presented: Cai Yangjian on June 15, 2006 Torbjörn Wass on October 3, 2006 Disala Uduwawala on October 6, 2006

o Two Licentiate theses were presented Valentinas Dubickas on April 27, 2006 Nathaniel Taylor on November 23, 2006

o 8 Master theses projects were completed.

o Lars Jonsson was appointed associate professor in November 2006

o Lina Bertling was appointed as assistant professor in June 2006. o Hans Edin received the Elforsk award for research in the maintenance field. o Eight new Ph.D: students were recruited. o The 9th International conference on probabilistic methods applied for power systems

(PMAPS) took place in 11-15 June 2006 with chairman Dr. Lina Bertling. The conference organized by the department gathered over 300 persons from around 35 different countries.

o Sailing He was one of the plenary speakers in SPIE (International Society for

Optical Engineering) Annual Meeting in San Diego, USA, August 13-17, 2006 o A new phase of the Competence Center on Electric Power Systems at KTH EKC2

has been started for the period 2006-2009 with an aim to continue during additionally four years. The Division has a major role in the program with Dr. Lina Bertling as manager for the research program on Maintenance Management involving nine PhD students, of six with the Division.

o A number new research projects have been granted

Competence centre maintenance management program for 4 years VR grant for 3 years on photonic metamaterials

4

Vindforsk contract for 3 years on maintenance management of wind power systems Elforsk contract for 3 years on risk methods Continuation for 2.5 years of two Elektra projects in insulation diagnostics Swedenergy contract on evaluation of the network performance assessment model

o A PhD course was given on Mathematical optimization models for maintenance management in collaboration with Applied Matematics at Chalmers/Applied Mathematics.

1 General resources 1.1 Personnel Electromagnetic engineering consists of the following individuals. E-mail addresses are composed as firstname.familyname@ee.kth.se: o Roland Eriksson Professor, head o Göran Engdahl Professor o Sailing He Professor o Staffan Ström Professor em o Lars Jonsson Associate Professor o Gunnar Larsson Associate Professor o Martin Norgren Associate Professor o Gunnar Pettersson Associate Professor em o Lina Bertling Assistant Professor o Hans Edin Assistant Professor o Patrik Persson Research Associate o Peter Fuks Senior Researcher o Sven Hörnfeldt Senior Researcher (until June 2006) o Yi Jin Post doc. (from August 2006) o Gulli Frohmader Administrator o Lars Austrin Ph.D. student o Yangjian Cai " " (until September 2006) o Valentinas Dubickas " " o Andres Ellgart " " o Cecilia Forssén " " o Anna Franzen " " (from May 2006) o Patrik Hilber " " o Xin Hu " " (from August 2006) o Andrea Lang " " (from December 06) o Tommie Lindquist " " o Julia Nilsson " " (from May 2006) o Mattias Oscarsson " " o Jörgen Ramprecht " " o David Ribbenfjärd " " o Johan Setreus " " (from June 2006)

5

o Jun Song " " (from August 2006) o Hanif Tavakoli " " (from December 06) o Nathaniel Taylor " " o Mohsen Torabzadeh " " o Dislala Udawawala " (until October 2006) o Carl Johan Wallnerström " o Torbjörn Wass " " (until October 2006) o Kristian Winter " " (from November 2006) 1.2 Economy The turnover of dividion was 22.9 MSEK. The grants were supplied by KTH (11.2 MSEK) and by external sponsors (11.7 MSEK). 1.3 Office facilities and laboratories The division has the following facilities: - high-voltage laboratory including a multitest set for 2x200 kV dc, 2x100 kV AC

and 400 kV impulse. - laboratory for static and dynamic measurements of magnetic materials

characteristics - laboratory for characterization of insulating materials by measurements of dielectric

response and partial discharges - laboratory for characterization of high-temperature superconductors - screened room for partial discharge mesurements etc. - antenna research laboratory. - various computers with software for dynamic simulations, and transient analysis

2 Undergraduate and continuing education 2.1 Undergraduate courses The undergraduate courses given by Electromagnetic Engineering are: 2A1800 Electrical Circuit Analysis (credit = 5) Peter Fuks Lectures 24h, Tutorials 30h

6

Ohm’s and Kirchhoff’s laws. Systems of equations. Transients. Complex representation of currents and tensions. Impedance and admittance. Complex power and impedance matching. Filters. Mutual inductive coupling. Transistors and operational amplifiers

2A1801 Applied Electronics (credit = 1) Peter Fuks

Lectures 6h, Laborations 8h , Seminaries 4h The course gives a “hands on” experience of design of electronic equipenent. The dominant part is a project during which the student will build a working prototype, solve ev EMC problems and design a scheme for fault finding. Syllabus: Passive and active componentsr. Tolerances. Frequency, power och tensions limitations. Discrepancies from simple models. Analog och digital building blocks. EMC. Security. Electronic design. Conventions. Prited circuits. Soldering. Fault finding. 2A1805 Electrical Circuits (credit = 5) Peter Fuks Lectures 32h, Tutorials 24h, Laboration 4h Ohm’s and Kirchhoff’s laws. Systems of equations. Digital signals in uncomplicated nets. Complex representation of current and tension, impedance and admittance. Impedance matching. Filters. Operational amplifiers. Simulation. Boole’s algebra. Logical gates. Karnaugh-diagram. Flip-flops. AD and DA converters. Basic measurements. 2A1810 Electromagnetic Theory EA (credit = 4) Gunnar Larson Lectures 29h, Tutorials 28h Electrostatics: Coulomb's law. Electric lines of force. Evaluation of electric field and potential in vacuum and with conducting and dielectric materials. Practical electrostatic problems. Energy and forces in electrostatic systems. Boundary-value problems. Method of images. Direct current: Ohm's and Joule's laws. The continuity equation. Boundary-value problems. Static magnetic fields: Biot-Savart's and Ampere's laws. Fields in magnetic materials. Magnetic circuits. 2A1820 Electromagnetic Theory EB (credit = 4) Gunnar Larson Lectures 29h, Tutorials 28h Electromagnetic induction: Transformation of electric and magnetic fields between systems with uniform velocity. Faraday's law. Mutual and self-induction. Energy and forces in static and quasi-stationary fields. Maxwell's equations: Applications of Maxwell's equations. Plane wave propagation and reflection. Radiation and reception of electromagnetic waves. Skin effect. Transmission lines. Antennas and radiating systems. 2A1840 Electromagnetic Theory F (credit = 6) Martin Norgren Lectures 50h, Tutorials 50h Part 1: Static fields Electrostatics: Coulomb's law and Gauss’ law. Electric lines of force. Evaluation of electric field and potential in vacuum and with conducting and dielectric materials. Practical electrostatic problems. Energy and forces in electrostatic systems.

7

Boundary-value problems. Method of images. Static magnetic fields: Biot-Savart's and Ampere's laws. Fields in magnetic materials.

Part 2: Time-dependent fields Electromagnetic induction. Faraday's law. Mutual and self-induction. Energy and forces in static and quasi-stationary fields. Maxwell's equations. Conservation laws. Plane waves: propagation, reflection and polarisation. Waveguides. Radiation and reception of electromagnetic waves Transformation of electric and magnetic fields between systems with uniform velocity.

2A1850 Electromagnetic Theory ME (credit = 6) Martin Norgren Lectures 50h, Tutorials 50h Part 1: Static fields Electrostatics: Coulomb's law and Gauss’ law. Electric lines of force. Evaluation of electric field and potential in vacuum and with conducting and dielectric materials. Practical electrostatic problems. Energy and forces in electrostatic systems. Boundary-value problems. Method of images. Static magnetic fields: Biot-Savart's and Ampere's laws. Fields in magnetic materials.

Part 2: Time-dependent fields Electromagnetic induction. Faraday's law. Mutual and self-induction. Energy and forces in static and quasi-stationary fields. Maxwell's equations. Conservation laws. Plane waves: propagation, reflection and polarisation. Waveguides. Radiation and reception of electromagnetic waves Transformation of electric and magnetic fields between systems with uniform velocity.

2A1860 Electromagnetic Theory CL, introductory course (credit = 4) Martin Norgren Lectures 36h, Tutorials 36h Coulomb's law and Gauss’ law. Electric lines of force. Evaluation of electric field and potential in vacuum and with materials. Energy and forces in electrostatic systems. Static magnetic fields:

Biot-Savart's and Ampere's laws. Fields in magnetic materials. Electromagnetic induction. Faraday's law. Mutual and self-induction. Maxwell's equations. Plane waves: propagation, reflection and polarisation.

2H1250 Electromagnetic Field Theory (credit = 5) Martin Norgren Lessons 40h, Project supervision 16h, Study visit 4h Maxwell's equations. The wave equation for electromagnetic fields and potentials. Constitutive relations. Gauges. Green's theorems and their application to the electrostatic and magnetostatic potentials. Green's functions and integral representations. Boundary value problems. Uniqueness theorems. Multipole expansions of static fields. Boundary value problems in spherical geometries. Conformal mapping methods for two-dimensional problems. Time-harmonic fields in wave guides: orthogonality relations and energy transport for TE- and TM-

8

modes. Excitation of waveguides from given sources; attenuation; the mode matching method; cavity resonators: TE-, TM, EH, and HE-modes in circular dielectric waveguides. 2H1255 Electromagnetic Wave Propagation (credit = 5) Staffan Ström, Lars Jonsson Lessons 56h Differential equations for the electromagnetic fields. Integral representation in finite and infinite domains. Radiation conditions. Electric and magnetic equivalent surface currents. Applications to reflector antennas. Approximate methods at high frequencies: Geometrical and physical optics. Electromagnetic multipole fields. Application to scattering from a sphere. Scattering cross section. Wave propagation from dipoles above the ground. Methods of stationary phase and steepest descent. The Null Field Method. Integral equation method for electro¬magnetic boundary value problems. 2A1830 Applied Antenna Theory (credit = 5) Gunnar Larson Lessons 50h, Laboration 18h The course takes a “hands on” approach. Projects and laborations are the principal part. The student will design different types of antennas, build them and measure their properties. The lectures discuss different antenna types such as wire antennas, aperture antennas, broadband antennas, small antennas and array, antenna feeds, antenna synthesis, system aspects on “transmitting – to – receiver” problems, propagation, numerical methods and different aspects of antenna measurements. 2C1134 Electrotechnical design (credit = 5) Göran Engdahl The course provides knowledge on how electrical, magnetic, mechanical and thermal problems are dealt with in design of electrical equipment and training of the ability to solve related design problems. The course gives the basics for solving these problems analytically and in project works examples of design problems on fields and dynamic systems treated by computer-based tools. Lectures 36 h, Laboratory 8 h, 4 Project works. 2C1132 High-voltage engineering (credit = 5) Hans Edin The course shall develop the participants' ability to solve problems related to high-voltage design. Project works are conducted on high-voltage measuring and testing technique and insulation diagnosis where the problems are studied experimentally and with computer-based tools. Lectures 22h, Laboratory 12 h, Project works 50h. 2C1133 Electrotechnical modeling (credit = 5) Göran Engdahl The course treats models for electrotechnical systems and components and how these models can be used for solving electrotechnical design problems and understanding of electrophysical phenomena. The course includes a number of individual tasks where the problem shall be formulated and a model developed for solving the problem.

9

Lectures, numerical workshops 28 h, 7 Project works. 2C1135 Reliability Assessment of Power Systems (credit=4) Lina Bertling This course treats reliability theory applied for electric power systems. The course shall give knowledge in using reliability assessment as a tool for decision support for; planning, operation and maintenance of the electric power system. The course is concentrated to 9 full lecture days and a final seminar, and involves work with an own project. The course is run together with the further education course 2C4030. Lectures 60 h including a computer lab. Project work. 2.2 Undergraduate theses During the year 9 master theses projects have been carried out for achievement of the university degree 'civilingenjör' or Master's degree, see publication list.

2.3 Continuing education 2C4535 Reliability Assessment of Power Systems (credit=4) Lina Bertling This is an advanced course for academics in the industry. The course is a condensed version of the further education course 2C4030, with the same name, and has the same content, course goal and examination form. The course is given on request, and was given for the first time for Vattenfall Eldistribution during autumn 2005. Electric Power Engineering Fundamentals Roland Eriksson This is a course for academics in the industry given upon request. The course gives an introduction to electric power engineering. 3 Graduate education 3.1 Graduate courses The division has two research subjects. Electromagnetic theory and Electrical systems. 3.1.1 Graduate courses, Electromagnetic theory F2H5051 Basic Electromagnetic Theory (credit=10-15) F2H5052 Analytic methods in electromagnetic field theory (credit=10-25) F2H5053 Electromagnetic fields in inhomogeneous media (credit=5-15) F2H5054 Numerical methods in electromagnetic field theory (credit=10-20)

10

F2H5055 Antenna theory and design (credit=10-20) 3.1.2 Graduate courses Electrical systems F2C5109 Graduate course in electric systems (credit=5-20) F2C5139 Graduate course in electrotechnical design (credit=5-20) F2C5107 Complementary graduate course in electrical systems (credit=5-20) F2C5060 Maintenance Management of Power Systems (credit=5 or 3, Lina Bertling This is a Ph.D. course for students at the Electrical engineering program. The course covers the topic of maintenance management divided into the four themes of: (1) Reliability data assessment and reliability modelling and assessment, (2) Reliability centred maintenance for maintenance optimization, (3) Condition monitoring and diagnostics methods and (4) Computer tools supporting techniques for maintenance planning. The course includes specialist lectures and own student work with an individual task. F2C5061 Mathematical optimization models for maintenance management (credit=3), Lina Bertling This is a Ph.D. course for students at the Electrical engineering program. The course aims to give an overview of an important type of mathematical models for maintenance optimization and the associated mathematical machinery – optimization theory and algorithms. The course is a two day course, consisting of a theoretical lecture series and a second day devoted to a practical study of a maintenance optimization model, including a project assignment. The examination for the course includes written; one-page computer exercise report, ten to fifteen page project report, and a five-page summary of the course and the project. 3.2 Graduate theses Valentinas Dubickas presented his licentiate thesis: On-line time domain reflectometry diagnostics of medium voltage XLPE power cables, April 27, 2006. Opponent: Dr. Tord Bengtsson, ABB Corporate Research, Västerås, Sweden. The thesis was supervised by Professor Roland Eriksson and Dr Hans Edin. Yangjian Cai presented his Ph.D. thesis: Propagation of Some Coherent and Partially Coherent Laser Beams, June 15, 2006. Opponent: Prof. Franco Gori, Univ. of Rome, Italy.. The thesis was supervised by Professor Sailing He. Disala Uduwawala presented his Ph.D. thesis: A Comprehensive Study of Resistor-Loaded Planar Dipole Antennas for Ground Penetrating Radar Applications, October 6, 2006. Opponent: Professor Olav Breinbjerg, Örsted-DTU, Denmark. The thesis was supervised by Associate professor Martin Norgren and Dr Peter Fuks.

11

Nathaniel Taylor presented his licentiate thesis: Diagnostics of stator insulation by dielectric response and variable frequency partial discharge measurements, November 23, 2006. Opponent: Dr. Jörgen Blennow, Chalmers Technical University, Sweden. The thesis was supervised by Professor Roland Eriksson and Dr Hans Edin.

4 Research activities The main part of the research aims at developing theory, methods and models for the design and application of electrical components and systems for electric power and telecommunication. Most of the work is carried out in interaction with industry or is inspired by problems in real apparatuses. The research is divided into five programs - Electromagnetic theory - Novel electromagnetic metamaterials - Electrotechnical modelling - Antenna theory and design

- Insulation diagnostics

- Reliability centered asset management (RCAM) 4.1 Electromagnetic theory The research group consists of:

• Lars Jonsson (Associate professor) • Martin Norgren (Associate professor • Jörgen Ramprecht (Ph.D. student) • Staffan Ström (Prof. em.)

The research is focused on the basic macroscopic electromagnetic laws as they apply to the generation and propagation of electromagnetic effects in vacuum, in material media, and in all the various devices that may be constructed to enhance, control, and utilize such effects. Thus the use and further development of all the methods - analytic, numerical, and also experimental - which are relevant for such an endeavour, are of prime interest to us. Somewhat more specifically, the main thrust of our research effort is in the area of propagation and scattering of electromagnetic waves. Progress in this area is crucial to the development of the various tools that are used so frequently in what is broadly referred to as the information society. This trend in modern society makes us increasingly dependent upon electromagnetic waves as carriers of information.

12

One of our main areas of research is direct and inverse scattering problems, both in the time and the frequency domain. In a direct scattering or propagation problem one considers the problem of determining the behaviour of an electromagnetic wave as it encounters an object or medium with known electromagnetic properties. In an inverse problem on the other hand, one analyses the way in which an electromagnetic wave has changed after it has passed through an unknown medium, and from this information one tries to infer the elec-tromagnetic properties of the medium. The proper understanding of electromagnetic information gathering devices (such as sensors) typically requires that one is able to solve, to some degree, a problem of the inverse type. Furthermore, design problems have much in common with inverse problems. The theoretical work ranges from studies of basic mathematical properties to numerical implementation of models relevant for specific applications. Non-linear effects are of great importance in many electromagnetic contexts, particularly in the context of high speed transmission over optical fibers. Progress in the theory of soliton propagation in such systems is then of obvious interest and the Division has recently become involved in basic research in that area. In addition to the greater mathematical understanding of nonlinear effects, such as uniqueness, well-posedness, blowups and asymptotics of the a number of nonlinear equations, we add physical understanding of complex nonlinear phenomena, both in electromagnetics as well as in other areas of physics. Dynamics and effective equations of several types of solitary waves has been the main focus for the last years. An increased focus on selected electromagnetic applications is foreseen 4.1.1 Inverse problems by means of higher order optimization NORGREN Martin (associate professor, Ph.D.) Martin Norgren has together with Prof. Takashi Takenaka from University of Nagasaki worked further on the inverse scattering problem for heterogeneous media by means of optimization. The seldom used full Newton's method has been considered as an alternative for solving the inverse transmission line problem in the frequency-domain. For the sake of accuracy and computational efficiency, the gradient and the Hessian of the cost-functional, with respect to parameter functions in the L2-space, have been derived explicitly by means of the adjoint transmission line problem and the first and second order Frechét differentials of the cost-functional. Hence, the results are formally independent of the method used in the numerical implementation. The generalization to the three-dimensional inverse scattering problem for bianisotropic media has been develop as well. The numerical implementation, when reducing to a finite dimensional parameter space, leads to a Hessian matrix that is highly ill-conditioned. The ill-conditioned Hessian was handled by using a zeroth-order Tikhonov regularization method, by means of a filtered singular value decomposition with a heuristically determined filter parameter. Although this approach worked quite well, it is desired to find a more theoretically based procedure for fixing the regularization parameter, likely some modified version of generalized cross validation or the L-curve method.

13

For the reconstruction of one or two parameters, the algorithm has been tested on synthetic reflection data contaminated with gaussian noise. The algorithm has also been tested on measured reflection data to reconstruct a piecewise constant shunt-capacitance. In both cases, the algorithm worked well. The additional calculation of the Hessian makes the full Newton method computationally slower than e.g. a gradient method. However, (quite expectedly) we observed that also in our application the full Newton method has a faster convergence (in terms of the number of iterations) than the conjugate gradient method, even though this may not compensate for the extended computation time. However, with the second order derivatives available, at a moderate computational cost, it is now possible to consider other optimisation methods based on complete second order derivatives. 4.1.2 Dynamics of nonlinear equations JONSSON, Lars (associate professor, Ph.D.) Since 2002, Lars Jonsson, together with I. M. Sigal, J. Fröhlich and S. Gustafson and others have jointly been working on the dynamics of nonlinear Hamiltonian systems, nonlinear Schrödinger equations (NLS), Hartree equations and semi-relativistic Hartree equations. We are interested in determining properties such as the dynamic behavior of the solutions, and conditions for global well posedness and blowup. The first of our results was to determination how solutions which initial are close to a (free) solitary wave behaves under the perturbation of a slowly varying bounded, smooth potential. This was first done for the NLS equation. The result of this work is now published in Comm., Math. Phys. 250(3) pp.613–642, 2004. The result states that for long times, the solitary wave's position follows Newton's second law. This result was later improved to include confining potentials and longer times; the result is published in Annales Henri Poincare, 7(4) 621–660, 2006. Similarly L. Jonsson together with S. Dejak studied similar questions for the Korteweg-de Vries and the results have now appeared in J. Math. Phys 47, 072703 pp. 1–16, 2006. The generalization of our NLS results to include the multi-soliton case is in progress. One of the utilization of this type of results is that we can estimate the position and the dynamical behavior of an almost solitary wave solution for long times, without solving the full, nonlinear PDE, numerically or otherwise. Such solitary waves appear in areas such as optics, Bose-Einstein condensates and as certain limits of Navier-Stokes equations. Currently, in work begun at the Department of Theoretical Physics, ETH, Lars Jonsson, J. Fröhlich and E. Lenzmann have considered the semi-relativistic Hartree equation. This has resulted into two papers (both now accepted (2007) as by journals articles) see ArXiv , math-ph/0503009 <http://arxiv.org/abs/math-ph/0512040>, and math-ph/0503009 <http://www.arxiv.org/abs/math-ph/0605053>. The first of these works treat the existence of ground states (solitons). The second of these papers extend the above works for NLS to the pseudo-relativistic Hartree equation, with modulation equations for solutions close to a

14

soliton. This equation is a model for Boson stars, and the external potential models the influence of the external gravitational field (e.g. from other stars). During 2006, we have initiated contacts with experimentalists on nonlinear optics to search for joint research problems. 4.1.3 Design of radar absorbers using magnetic materials RAMPRECHT, Jörgen (Ph.D. student) NORGREN Martin (associate professor, Ph.D.) Jörgen Ramprecht and Associate Prof. Daniel Sjöberg (Lund University of Technology) have during 2006 started an investigation about using nonlinear magnetic hysteresis media in broadband microwave absorbers. Usually it is important to have good absorption over a wide range of frequencies. Due to their inability to absorb power for low frequencies, materials based on purely dielectric phenomena and electric losses are often considered unsuitable for a broadband absorber design where the available physical space is limited. Therefore it is of interest to investigate whether a material with magnetic losses can be used for the purpose of obtaining thin absorbers that also copes with the broadband requirement. Using magnetic materials in absorbers seems to be an area that is not as well explored as its dielectric counterpart, although practical designs have been in use for a long time.

One crucial point in the process of designing an absorber is to understand the loss mechanisms of the materials used and how they shall be modelled. In this project, the magnetic media are modelled by the Landau-Lifshitz (LL) and the Landau-Lifshitz-Gilbert (LLG) equations. By taking into account the first order perturbations from the static equilibrium solution, a linearised small-signal model has been developed for a special case, resulting in an equivalent permeability tensor and equivalent magnetic conductivity tensor. The linear model has been incorporated into a scheme for computing the reflection coefficient for a plane wave impinging normally onto a planar magnetic layer on an electrically perfectly conducting surface.

Another consideration is to develop homogenization methods in order to realize composite absorbing materials, by mixing inclusions of magnetic media into a non-magnetic host material. Eventually, we plan to investigate whether absorbing magnetic media can be used in phased-array antennas to suppress surface waves, in order to increase the bandwidth.

4.2 Novel electromagnetic metamaterials The research group consists of:

• Sailing He (Professor) • Peter Fuks (Senior Researcher, Ph.D.)

15

• Xin Hu (Ph.D. student) • Jianqi Shen (Ph.D. student) • Jun Song (Ph.D. student)

One important trend is that of using higher and higher frequencies, which makes it possible to use smaller and smaller devices. This in turn calls for full electromagnetic field compu-tations for e.g. devices in optical communication systems. The Division is actively involved in these new developments, in particular through its participation in the recently created Joint Research Centre for Photonics of KTH and Zhejiang University. A key person enabling this collaboration is Prof. Sailing He, who shares his time between KTH and Zheijang University, where he is Director of the Centre for Optical and Electromagnetic Research. An important part of the research concerns propagation and scattering of waves in new types of complex materials, including materials with negative permeabilities and permittivities and their applications in the design of new types of optoelectronic devices. 4.2.1 Project 1 Jianqi Shen and Sailing He have studied the possibility of the backward waves and negative refractive indices of the gyrotropic chiral materials, and derived the impedances of the eigenmodes. It is shown that the negatively refracting medium can be achieved even far off the resonances of the permittivity and permeability. A potential effect of the field quantization in a compact subwavelength cavity resonator containing the gyrotropic chiral material is suggested in this work (JOURNAL OF PHYSICS A, 39 (2): 457-466, 2006). Jianqi Shen, Martin Norgren and Sailing He have also studied some nontrivial effects (negative refraction and quantum vacuum effects) in gyroelectric chiral medium and magnetoelectric material. It is shown that the refractive indices corresponding to some of the eigen modes in the gyroelectric chiral medium and magnetoelectric material may have negative real parts since both the gyroelectric and magnetoelectric parameters can dramatically reduce the refractive indices in certain frequency bands. As an anisotropic electromagnetic environment could be created due to the breaking of universal symmetry of vacuum mode distribution (and hence the noncompensation effect of a pair of counter-propagating vacuum modes arises) inside the magnetoelectric material, the quantum vacuum in such an anisotropic electromagnetic environment may have a nonzero angular momentum. A novel quantum vacuum effect (angular momentum transfer between the quantum vacuum and the anisotropic magnetoelectric material) that may accompany the effect of magnetoelectric negative refraction is suggested. This work is published in ANNALEN DER PHYSIK (15 (12): 894-910, 2006). 4.2.2 Project 2 Yi Jin and Sailing He have studied the conditions for the existence of surface polariton modes on the surface of a half-space or slab of such a chiral medium. Numerical results for pure and quasi surface polariton modes are given for three typical chiral slabs. The net energy flux of the guided waves related to these surface polaritons may flow forward, backward or even be stopped. Surface polaritons of such a chiral slab can be used to slow

16

down the light effectively. The work is published in PHYSICS LETTERS A, 351 (4-5), 354-358, 2006. They have also suggested a wedge cavity within two metallic plates by filling half of the cavity with a photonic crystal with a negative effective index. The eigen frequencies and quality factors of the modes are studied with the finite element method. Phenomena associated with this open wedge cavity are explained physically. A potential application of this novel cavity as a gas sensor is also studied. The work is published in IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS (16 (11): 582-584, 2006). 4.2.3 Project 3 Jun Song and Sailing He have studied planar lightwave circuits for optical communications. They have designed an etched diffraction grating (EDG) demultiplexer with sidelobes suppressed by etching two optimized rectangular air trenches in front of each output waveguide. The work has been published in JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A (23 (10): 2645-2649, 2006). They have also designed echelle grating demultiplexers with reduced return loss. The input waveguide is placed on the minimal intensity position of the diffraction envelope. Then, by further chirping the diffraction order for each facet, they minimize the envelope intensity for other adjacent diffraction orders. The present design is appropriate for multifrequency laser or multistage demultiplexer applications and the work is published in IEEE PHOTONICS TECHNOLOGY LETTERS (18 (13-16): 1506-1508,2006). In their another work in JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A (23 (3): 646-650 MAR 2006), they have also analysed fabrication tolerance of surface roughness on the performance [such as the insertion loss, the polarization-dependent loss (PDL), and the chromatic dispersion] of an etched diffraction grating demultiplexer. 4.2.4 Project 4 Yangjian Cai and Sailing He have studied the propagations of various beams in some turbulent atmospheres or optical systems. First they investigated the propagation of a dark hollow beam (DHB) of circular, elliptical or rectangular symmetry in a turbulent atmosphere. Analytical formulas for the average intensity of various DHBs propagating in a turbulent atmosphere are derived in a tensor form based on the extended Huygens-Fresnel integral. It is found that after a long propagation distance a dark hollow beam of circular or non-circular eventually becomes a circular Gaussian beam (without dark hollow) in a turbulent atmosphere, which is much different from its propagation properties in free space. This work is published in OPTICS EXPRESS (14 (4): 1353-1367, 2006). In their paper published in APPLIED PHYSICS LETTERS (89 (4): Art. No. 041117, 2006), they have derived the analytical formulas for the propagation of a partially coherent twisted anisotropic Gaussian Schell-model beam in a turbulent atmosphere. They have also derived an analytical formula for the average intensity of an elliptical Gaussian beam (EGB) propagating in a turbulent atmosphere (OPTICS LETTERS, 31 (5): 568-570, 2006). In their work in JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A (823 (6): 1410-1418, 2006), they have derived an approximate analytical formula for a hollow Gaussian beam propagating through an apertured paraxial stigmatic (ST) ABCD optical system. By using a

17

tensor method, they derived approximate analytical formulas for a hollow elliptical Gaussian beam propagating through an apertured paraxial general astigmatic ABCD optical system and an apertured paraxial misaligned ST ABCD optical system. In their another paper in JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A (23 (10): 2623-2628, 2006), they proposed a simple model called partially coherent flattened Gaussian beam (FGB) to describe a partially coherent beam with a flat-topped spatial profile. An explicit and analytical formula is derived for the cross-spectral density of a partially coherent FGB propagating through a paraxial ABCD optical system. The propagation factor and propagation properties of a partially coherent FGB in free space are studied in detail and found to be closely related to its coherence and beam order. 4.2.5 Project 5 Peter Fuks and Zhichao Ruan prepared an experiment on focusing electromagnetic waves using photonic crystals during the most of the 2006 . The idea originates from the optical domain but because of the very high cost of manufacturing we decided to scale down the experiment to the microwave range (around 2,5 GHz). The first step consisted of finding a material with suitable electrical properties which proved very time consuming. The manufacturers usually publish only low frequency parameters so it was necessary to develop a test cell for high frequency measurements. Both time domain and frequency domain measurements on a large number of different compounds were made and a promising one (unfortunately expensive and poisonous) was selected. We also designed and build the periodic structure itself, a suitable transmitting antenna and sonds for probing the field. Our 2D scanner was adopted for the measurements which will be performed during 2007. The work was done in collaboration with Min Qui and Zhichao Ruan from Department of Microelectronics and Applied Physics. 4.3 Electrotechnical modelling The research group consists of:

• Göran Engdahl (Prof., main supervisor) • Lars Austrin (Ph.D. student) • Mattias Oscarsson (Ph.D. student) • David Ribbenfjärd (Ph.D. student) • Mohsen Torabzadeh-Tari (Ph.D. student) • Hamid Moradi (Ph. D. student)

This research area comprises development of theory, methods and tools for electric power components including magnetic and other materials. The governing approach is to model material related electrotechnical phenomena and processes by use of Maxwell’s equations and material algorithms in a system perspective.

18

Since the middle of the 80’s a number of projects have been performed regarding characterization and modelling of apparatus and systems comprising magnetostrictive and magnetic materials. That work has been focused on characterization and modelling of magnetic materials. Since the middle of the 90’s the activities also include modelling of transformers, electromechanical actuators and power electronics, electromachines and magnetic amplifiers for aircraft applications. A magnetic and materials modelling laboratory has been built up around characterization of magnetic and functional materials. The outcome of these measurements are stored in databases and thereafter used as input to computer algorithms included in simulation programs. These programs are finally aimed at helping engineers and scientists in electrotechnical design projects. The activities of the modelling group during the year has been related to

• Magnetic hysteresis • Power transformers • Electromechanical actuators • Magnetostrictive actuators • Magnetic amplifiers • Power supply systems • Cooling systems

Some recent results are:

• Improved algorithm for extraction of hysteresis model parameters • Improved algorithm for static hysteresis • Created, simulated and experimentally verified dynamic hysteresis model for core

material with poor field penetration • Optimisation of an electromechanical actuator for More Electric Aircraft

applications • Analysis of a pulsed power supply system for unmanned aerial vehicle • Optimisation approach of coil and magnetic circuit of magnetostrictive actuators.

4.3.1 Applied magnetostriction – Design tools and experimental methods ENGDAHL, Göran (professor, Ph.D.) OSCARSSON, Mattias (Ph.D. student) Giant magnetostrictive materials are used in underwater sonar applications, high-pressure pumps, active vibration control, damage analysis and other sensor applications. However, the design of magnetostrictively based technology is by no means standardized and no commercial design tools are available. Therefore, design methods and computer aided tools for the modeling and design of giant magnetostrictively based systems have been developed in this project for several years, and have now become a valuable and unique

19

design tool. The code is today by no means user-friendly but more a model for the specialist. An attempt has now been done to make the code user-friendlier. The old code is also under conversion to a modern software environment for simulation of dynamic systems as DYMOLA and MATLAB. An experimental evaluation system for dynamic measurements and assessments of magnetostricitive actuators has been constructed and further developed. A measurement and data acquisition system has also been installed, with the possibilities of advanced control and data processing. The experimental evaluation and data acquisition systems have been tested using several magnetostrictive actuators of different design. These tests show that the experimental evaluation system is functioning as a well-defined test environment for magnetostrictive actuators. The experimental evaluation system has also been equipped with a new electronic device developed at the department to automatically control the mechanical pre stress level on the actuator. (Sponsored by EU) 4.3.2 Transformer modeling for development of the FRA method for life time estimation

and risk management

ENGDAHL, Göran (professor, Ph.D.) TAVAKOLI, Hanif (Ph.D. student) The overall goal of this project is to develop a transformer model that can be used for further development of the FRA method. The Frequency Response Method (FRA) makes it possible to detect changes of the electrical properties and the geometrical shape the transformer core and windings. Thus information regarding the condition and reliability of the transformer can be obtained for life time estimation and risk management. The project includes further development of the existing electromagnetic model including the ferromagnetic core and use of it for the interpretation of so-called FRA-spectra. This project is closely related to another project within EKC2 on life time modelling and management of transformers. (sponsored by the Competence Centre in Electral Power Engineering at KTH, EKC2) 4.3.3 Electromagnet transformer modeling including the ferromagnetic core

ENGDAHL, Göran (professor, Ph.D.) RIBBENFJÄRD, David (Ph.D. student)

20

The purpose of this research project is to further develop models for dynamic simulation and loss calculations in transformers. The project builds on a number of other projects that have been performed at the department in recent years, regarding characterization and modeling of magnetic materials in electrotechnical apparatuses and systems. The losses in transformers include hysteresis, eddy currents, skin effect and leakage flux. The aim is to investigate these losses in detail and make more exact models for them. The intention is that these models should be usable in transformer design, studies of transient operation modes and diagnostics of the physical condition of transformers. During the year the static hysteresis model has been further developed to give better agreement with measurements. A dynamic hysteresis model has also been further developed. Measurements have be done for verification of the models. (Sponsored by the ELEKTRA program) 4.3.4 New electrical components for aircrafts (MEA-systems)

ENGDAHL, Göran (professor, Ph.D.) AUSTRIN, Lars (Pd. D. student) TORABZADEH-TARI, Mohsen (Pd. D. student) The project constitutes a continuation of a previous project MEA with the object to find technology for upgrading the electric power system in existent aircrafts or technology for further and new development of aircrafts. This project comprises analysis and development of methods for dimensioning of new electrical components for aircrafts as electrical machines, power electronics, magnetic amplifiers etc. The intention is that the new technology will imply lower costs, reduced weight and maintenance and improved reliability and performance. The project is performed in close collaboration with Saab. (Sponsored by NFFP) 4.3.5 Magnetoelastic energy systems for even more electric aircraft

ENGDAHL, Göran (professor, Ph.D.) OSCARSSON, Mattias (Ph.D. student) MESEMA Magnetoelastic Energy Systems for Even More Electric Aircraft is a technology oriented research program that builds upon the success of previous EU projects with devotion to accomplish the objectives of the aeronautics priority through designing, producing and testing "innovative transducer systems based on active materials".

21

The applications transducers for high-torque actuation, vibration and noise reduction, electrical energy generation and structural health monitoring is covered by the project. Four aircraft companies and fourteen SMEs and university research institutes participates. The institution is active in concept creation, design and modeling concerning transducers for high-torque actuation and electrical energy generation. (Sponsored by EU) 4.3.6 Controllable reactor with HTS control winding

HÖRNFELDT, Sven (professor, Ph.D.) WASS, Torbjörn (Ph.D. Student) The controllable reactor is mainly used in tuneable filters to eliminate unwanted harmonics that are generated in HVDC stations. The main disadvantage with the current design is the ohmic losses in the control winding. Besides, the limited current density in normal conductors (copper or aluminium) limits the dynamic range of the reactor. A control winding made of a HTS will lower the losses and will also increase the dynamic range due to the higher current density. The control winding will carry a rather large DC-current and simultaneously be exposed to an alternating magnetic field from the AC-coil. For the part of the control winding that is situated inside the core this AC-field is parallel to the direction of the DC-current while for the part of the winding that is outside the core the field is perpendicular to the DC-current. The undertaking of the project was to investigate an HTS to find out the design criteria for an optimised control winding. To obtain this the losses in the tape was investigated under the circumstances discussed above. Models of how these losses vary with temperature, applied magnetic field, current and frequency has been developed. From these models an optimised control-winding can be designed. A calorimetric loss measuring set-up has been designed and constructed. A 6 kVA controllable reactor with a control winding of HTS tape has been designed and constructed. The design has some important advantages compared to a copper control winding. The dynamic range of the reactor is dramatically increased and the weight, size and losses are substantially reduced. The project has been completed and presented in a Ph.D. thesis. (Sponsored by the ELEKTRA program and ABB) 4.4 Antenna theory and design The research group consists of:

• Lars Jonsson (Associate professor) • Martin Norgren (Associate professor • Patrik Persson (Research associate, Ph.D.)

22

• Peter Fuks (Senior Researcher, Ph.D.) • Anders Ellgardt (Ph.D. student) • Disala Udawawala (Ph.D. student)

Electromagnetic waves are launched and received by antennas. In response to the needs created by the above-mentioned trends, antenna theory and design has become another main area of research. The focus is on the development of new analytic and numerical methods of importance for the design of advanced antenna configurations, such as broad-band antenna arrays and antenna arrays conformal to some prescribed (curved) surface. A new area, which is vigorously pursued, is antenna applications exploiting the band structure of photonic crystals. 4.4.1 Conformal Antennas An important milestone in 2006 was the publication of the book Conformal Array Antenna Theory & Design. The book was released in February 2006, published by Wiley-IEEE Press. Until the end of June 2006, more than 600 copies were sold. Currently, the book is on review within the IEEE AP-S community and a review is expected to be published in the IEEE AP Magazine in the near future. The work within the EU Sixth Framework Programme, ACE (Antenna Center of Excellence) has continued. KTH/ETK (P. Persson) is mainly involved in the ACE WP 2.4-3 “Structuring Research on Conformal Antennas”. One part of the plan for 2006 was to continue the development of the hybrid spectral domain – UTD method for analyzing conformal antennas. This work is the result of joining research activities of CHALMERS, KTH/ETK and University of Zagreb, Croatia. During 2006 the hybrid method has been extended to handle any convex singly curved surface with or without dielectric layers. Both mutual coupling results and radiation patterns for an elliptic cylinder has been studied and verified against results obtained using CADT (Conformal Antenna Design Tool, developed by Patrik Persson) and Flomerics Microstripes (a commercial software based on a 3D TLM approach). The results agree very well with each other. The method was presented at Antenn06 and at EUCAP2006. The plan for 2007 is to generalize the code further to handle doubly curved surfaces as well. The second part is about studying beamforming algorithms for conformal antennas. The work has focused on direction of arrival algorithms (MUSIC and ESPRIT) and on adaptive beamforming algorithms (Capon’s algorithm and the LMS method). In addition, KTH/ETK (P. Persson) was involved in the ACE course titled: Analysis of planar and conformal antennas. P. Persson taught about high frequency methods for analysis of conformal antennas as well as giving numerous of examples discussing the EM properties of conformal antennas. The course was held at EPFL, Lausanne, Switzerland, Feb. 27 – Mar. 3, 2006. 2006 was also the first year of the Charmant project, funded by SSF. This is a joint antenna research program and the Charmant Center is located at Chalmers. KTH/ETK (P. Persson) is one of several nodes and our task during 2006 was to start working with antenna system aspects of conformal antennas. The work has been focused on applying different DOA

23

(direction of arrival) algorithms and different adaptive beamforming algorithms on conformal antennas. In the long term perspective such models are supposed to be used in the antenna system simulator to be developed within Charmant. The research was coordinate also with the ACE project described above and with Maria Lanne at Chalmers/S2. Collaboration was also established with Dr. Thomas Rylander at Chalmers/S2, the goal was to set up interesting optimization problems for conformal antennas applications. Several meetings were held during 2006. 4.4.2 Broadband antennas Broadband antennas is a project that has been going on for some time, However, 2006 was the last year of this project funded by FOI/FMV. The long term goal with this project has been to look into the field of thin broadband antennas. Lately, the focus has been on fragmented patch antennas and the main goal for 2006 was to design, build, and measure a couple of fragmented patches. The experimental part was a collaboration with Hans Steyskal at Airforce research Lab, Hanscom, MA, USA. The idea was to use designs obtained with a genetic algorithm during 2005. However, it turned out that the designs was not suitable to be used. The results were very sensitive on grid resolution in the simulations, especially when scanning, and the material parameters optimized were difficult to find in practice. Thus, much work was spent on redesigning the antennas with respect to given material parameters. Due to the limitations in materials it was not possible to get as good bandwidths as in the designs made during 2005. About 1 octave was possible to get with the given parameter set up. As a consequence of the redesign no measurements were done during 2006. Another important area is to look at the feeding models for the fragmented patches. Up to date, a simplified idealized feeding is used but in practice a realistic feeding has to be used. Some minor work was done on this topic during 2006. Theoretical, several designs may be possible to use but they are often decreasing the bandwidth. A solution to this problem is yet to be found. 4.4.3 Wide scan and wide-band array antennas The project is a collaboration with Ericsson Micro Wave (EMW) and KTH/ETK (A. Ellgardt) within NFFP4, FLYGANT, started in spring 2006. The goal with the project is to perform research on wide-scan and wide-band phased array antennas. A part of the project is to design an experimental antenna and perform measurements to verify the design. The experimental antenna is a step towards a phased array nose radar for a aircraft but could also be used for other applications such as maritime or ground to air radar. The specification for this antenna was written by EMW and designed by KTH and resulted in a single polarized tapered notch element capable of 60° scan angle from broadside in all planes for a bandwidth of 2.5:1 for SWR<2. Extra effort has been made to reduce the radar cross section (RCS) of the antenna. An absorbing layer covers the groundplane to reduce the RCS from the orthogonal polarization of the antenna, and the bandwidth of the antenna is larger than necessary to reduce RCS for the operational polarization. Antenna measurements are going to be performed in the spring of 2007 by EMW, but the antenna will also be available for further measurements afterwards.

24

The continuation of the project is to study edge effects for a finite array. The antenna elements at the edges of a phased array behave differently than the elements in the middle of the antenna. This effect is due to that the elements in the phased array couples to the neighbouring elements. The truncation effects are difficult to study with numerical codes due to the size of the antenna, and analytical solutions only exists for simplified elements such as delta-gap fed dipoles. An initial problem to study is an antenna that is finite in one direction. This will reduce the size of the problem, but still give useful information of the performance of the finite array. 4.4.4 Subsurface radar antenna design UDUWAWALA, Disala (Ph.D. student) NORGREN Martin (associate professor, Ph.D.) FUKS Peter (Senior Researcher, Ph.D.) During previous years extensive simulations have been carried out for the design of a wide-banded dipole antenna (a so-called bow-tie antenna) to be used in a ground penetrating radar (GPR) system. During the final phase of the project, the results from the simulations were compared with results from measurements. Two identical prototype antennas (one for transmitting and one for receiving) have been built. Results from time and frequency domain measurements in open air were compared with results from finite difference time domain (FDTD) simulations. The results were shown to be in good agreement, despite the inherent problems in the matching network of the antenna. Outdoor measurements were carried out on different objects buried in snow. The selected objects were a 75 cm times 65 cm metal sheet, a metal pipe with 15 cm diameter, and an air-filled plastic pipe with 11 cm diameter and 5 mm thickness. The objects were buried one at a time at the depth of 50 cm, and the snow heap was about 1m above the ground. The same antenna setup and the incident pulse as in the indoor measurements were used. The results show that this type of antenna is promising for GPRs working in the low GHz frequency range and seeking a depth of penetration of around 1m. The project ended in October 2006, when Disala Uduwawala successfully defended his Ph.D. thesis. This project was funded by Swedish International Development Agency (SIDA). 4.5 Insulation diagnostics The research group consists of:

• Roland Eriksson (Prof., main supervisor) • Hans Edin (senior lecturer, assistant supervisor) • Per Pettersson (Ph.D., guest researcher) • Valentinas Dubickas (Ph.D. student) • Cecilia Forssén (Ph.D. student) • Nathaniel Taylor (Ph.D. student)

25

• Kristian Winter (Ph.D. student) From Nov. 2006 The integrity of the electrical insulation is of greatest importance in the reliability of high voltage equipment. Failure of the insulation system may cause an interruption of service, or in worst case a complete damage of the equipment with a costly replacement. The research work aims at developing practical and reliable methods that can diagnose the degradation status of the electrical insulation. The results from diagnostic methods can be used in long-term maintenance strategies but also for short-term estimates of the failure risk in relation to the risk. The diagnostic techniques under investigation are based on measurement of different kind of dielectric response. Low-frequency dielectric spectroscopy is developed as a general tool to diagnose degraded insulation systems. The applicability of high-frequency methods for a more precise localization of defect insulation is under development. Partial discharge activity is measured and analyzed when the insulation system contain voids, delaminations, cracks or over-stressed surfaces, etc., that may cause local discharges. Research on new composite materials with SiC for field grading applications is performed as an industrial Ph.D. project at ABB. This would give a possibility to optimize the field control in highly stressed devices like, for example, cable terminations. 4.5.1 Physical modelling of partial discharges at variable frequency of applied voltage EDIN HANS, Hans (Ph.D.) FORSSÉN, Cecilia (Ph.D. student) The aim of the project is to increase the understanding of measurements of partial discharges at variable frequency (VF-PRPDA) and to relate the measured quantities to the physical properties of the electrical insulation. An increased understanding of this relationship would improve the possibilities to judge the condition of the insulation and to estimate the risk of failure for an insulation system, for example cable insulation or machine insulation. The results to be obtained from the project are: - A model of partial discharges at variable frequency of applied voltage. Physical properties of interest are the material parameters and their dependence on temperature, frequency, moisture content and ageing; and the geometry of a cavity, its shape, location and discharge behaviour. - Measurements on simplified test objects to validate the model. - List of characteristics for different PD sources that can be used for interpretation of complex measurements on complete insulation systems.

26

The results from the project so far are: - The VF-PRPDA technique has been applied to a test object containing a cylindrical cavity in an otherwise homogeneous insulation of polycarbonate. The frequency of the applied voltage was varied in the range 10 mHz – 100 Hz. It was concluded that with the VF-PRPDA technique, it is possible to distinguish between cavities of different size and between insulated cavities and cavities placed against an electrode. - A field model of PD in an insulted cylindrical cavity at variable frequency of the applied voltage has been created. (Sponsored by the Competence Centre) 4.5.2 Dielectric diagnostics of machine insulation by dielectric spectroscopy and variable

frequency phase resolved partial discharge analysis EDIN, Hans (Ph.D) TAYLOR, Nathaniel (Ph.D. student) Previous work at the institution has developed the use of variable applied frequency in measurements of dielectric response and phase-resolved partial discharges. The aim of this project is to investigate the application of these extended dielectric response and partial discharge methods to the specific case of insulation systems in large rotating electrical machines such as power-station generators and large industrial motors. These machines' insulation systems are based on mica flakes in a bituminous or epoxy binding. Sites of partial discharges and degraded dielectric properties may be in the insulation between conductors, or between conductors and the earthed stator iron, or in the end-winding region where high axial fields on the insulation surface may exist and are moderated by semiconducting coatings. Use of the variable-frequency methods together is expected to allow better localisation and specification of insulation problems. Adaptations to existing equipment are needed to obtain a system that can make all required measurements rapidly, accurately and with a large extent of automation to reduce errors during repetitive tests. Measurements will be made upon insulation systems in machines in the field and on bars of various condition. From these measurements, knowledge and understanding of the usefulness and meaning of information from the advanced diagnostic methods will be obtained, leading to a methodology for insulation system assessment. Field measurements have been performed on a hydro-power generator. New stator coils have been thermally aged with an accelerated thermal ageing procedure. The thermal ageing introduced defects that after the ageing suffered due to partial discharges. A licentiate thesis was presented on November 23 2006.

27

(Sponsored by the ELEKTRA program) 4.5.3 On-line diagnostic methods for power cables EDIN, Hans (Ph.D) DUBICKAS, Valentinas (Ph.D. student) For this day the most common power cable insulation diagnostic techniques are off-line, the cable is disconnected from the grid during the diagnostics. Partial discharge detection and dielectric loss measurements diagnostics are successfully used off-line. New technique, time domain reflectometry, is being developed in our department. It should allow water trees growing in the insulation to be localised. Development of an on-line diagnostic system for the power cables’ insulation is the goal of the project. The work is concentrated on the Time Domain Reflectometry (TDR) technique application for measurements on-line. The on-line measurements are performed while the power cable is connected to high voltage and is supplying the load. Therefore high voltage and the load variations could be used as a differentiating parameter in the diagnostics. However in order to perform the on-line measurements the couplers are needed to decouple the measuring equipment from the high voltage. Four types of couplers were built: inductive coupler, Rogowski coil, capacitive coupler and coupling capacitor. The couplers were investigated and high frequency models were built. Temperature dependence upon pulse propagation was investigated both in laboratory and in field-measurements by studying the consequence of load cycling. Results from these investigations were presented on Conferene on Electrical Insulation and Dielectric Phenomena (CEIDP) in Kansas City, USA in October 2006. Field measurements were performed on Vattenfalls 24 kV net in Botkyrka. An on-line copupling capacitor principle was tested for TDR experiments. A licentiate thesis was presented on April 27 2006. (Sponsored by the ELEKTRA program) 4.5.4 Diagnostic criteria and new diagnostic methods for machine insulation EDIN, Hans (Ph.D) WINTER, Kristian (Ph.D. student) This project was started in novemeber 2006 with the aim to develop criteria of machine stator-insulation degradation based on a comparison of electrical measurements like dielectric spectroscopy, variable frequency partial discharge analysis, surface conductivity analysis and physico-chemical analysis methods. Within the project, new excitation and detection/analysis methods will be tested.

28

(Sponsored by the Competence Centre) 4.6 Reliability Centred Asset Maintenance (RCAM) The research group at KTH consists of:

• Roland Eriksson, (Prof., main supervisor) • Lina Bertling, (Ph.D., project leader and assistant supervisor) • Anna Franzén (PhD student) • Patrik Hilber (PhD student) • Andrea Lang (PhD student) • Tommie Lindquist (PhD student) • Julia Nilsson (PhD student) • Johan Setréus (PhD student) • Carl Johan Wallnerström (PhD student)

Maximal asset value and minimal life cycle cost are examples of stated tasks of the electric power system managers. However, these tasks are constrained by the requirements of customers and regulators concerning the reliability of power supply. The de-regulation of the electricity market has increased the incentives for a cost effective and efficient use of available assets. Maintenance is one of the tools for achieving these goals, and utilities need to implement new strategies for more effective maintenance techniques and asset management methods. The generally known reliability-centered maintenance (RCM) method defines cost-efficient maintenance programs. However the method is generally not capable of showing the benefits of maintenance on system reliability and costs. A reliability-centered asset maintenance (RCAM) method has been developed at the division (Bertling 2002). This approach improves the RCM method by providing quantitative results when: relating the effect of maintenance on component failure rates to the system reliability, and for comparing the costs of different maintenance strategies. The overall objective for this research group is to further develop the RCAM for an optimal handling of assets in the electric power systems, as well as the own expertise in the area. The research group has the following research focus;

• maintenance planning and optimization including reliability-centered maintenance (RCM) methods

• reliability modeling and assessment for complex systems

• lifetime- and reliability modeling for electrical components

with application areas of; distribution systems, transmission components (breakers, disconnectors, and transformers), hydro power, wind power, HVDC and nuclear power.

29

During the year the RCAM group has been extensively extended including five new PhD students. Three PHD students have started within the research program on Maintenance management within EKC2 (Anna Franzén, Julia Nilsson and Johan Setréus), of two made their Master theses with the RCAM group. One student has started his PhD studies after working as a researcher within the RCAM group since 2005 (Carl Johan Wallnerström). One PhD student was recruited for the new project on wind power systems (Andrea Lang). Two PhD students have returned after research visits abroad and parental leave (Tommie Linquist and Patrik Hilber). The RCAM group has a strategy day in November to plan for the future work. There are currently six master theses projects within the group. One is associated with the research project on maintenance optimization of electrical networks, one with the wind power research project, three with the research project on reliability modeling with application focus on HVDC, and one with the project on life time modeling of transformers. The group is also active in IEEE PES committees and in several steering groups at Elforsk and Svensk Energi. 4.6.1 Reliability centered asset management BERTLING, Lina (Assistant Professor, Ph.D.) This post-doctoral project aims to further develop the reliability-centred maintenance method, with the overall goal to optimise the maintenance achievements and support cost-effective strategies for power systems. The developed RCAM method is refined to further investigate the component reliability for a general application of the method, and by incorporating optimization methods to obtain the maximum asset value. The research within this area is made related to the ongoing PhD and MSc projects within the RCAM project. During the year five new PhD projects have been started with different focus for further developing the RCAM method, and one new PhD course has been developed within maintenance optimization. (Sponsored by the Competence Centre in Electrical Power Engineering at KTH, EKC2 and KTH) 4.6.2 Life time modelling and management of transformers BERTLING, Lina (Assistant Professor, Ph.D.) FRANZÉN, Anna (PhD student) The goal for this project is to develop a quantitative probabilistic model, based on both failure statistics and measurements, for the life time of a transformer component. First models for life time estimation of transformers and measurements techniques will be studied. Then an improved model will be developed. Finally the developed model will be

30

implemented into a maintenance planning problem as input data for the RCAM system reliability analysis. During the autumn a research visit has been made with EON distribution to study the transformer populations. Work is also performed within a master thesis project by Sabina Karlsson which focuses on developing statistical method for life time estimation based on results from Dissolved Gas Analyses. This project is closely related to another project within EKC2 on transformer modelling with focus on developing the Frequency Response Analysis method for diagnostic of transformer condition. During the autumn two workshops have been held for discussions and collaborations within the joint focus on transformer modeling. (Sponsored by the Competence Centre in Electrical Power Engineering at KTH, EKC2) 4.6.3 Development of optimization methods for maintenance considering reliability and

costs BERTLING, Lina (Assistant Professor, Ph.D.) HILBER, Patrik (Ph.D. student, Tech. Licentiate) A reliability-centred maintenance method has been developed within previous research work at the division. This project constitutes a continuation and improvement of the developed method. The project works toward an optimization method for the determination of the optimal balance between preventive and corrective maintenance in order to obtain the lowest total cost. As a first step the project started with an analysis of the level of outsourcing for maintenance activities as a part of a process description of the maintenance routines for transmission and distribution networks. As a second step, toward the objective, methods for identification of component reliability importance in electrical networks were developed. The component reliability importance measures constitute a connection between component performance and the total system performance, which is a central aspect when building a maintenance optimization routine. During 2004 and 2005 an application study of the rural network of Kristinehamn was performed applying these methods. The resulting component prioritization lists represent a significant step towards the main objective of maintenance optimization. During a research visit to the research institute INESC Porto in Portugal (October 2005-March 2006) a framework for maintenance optimization was developed, built on previous methods. The last large activity in the project before completion is a case study that will be performed during 2007. This case study is expected to further improve the developed methods as well as to constitute a confirmation of the applicability of the developed methodology. (Sponsored by the Elektra program)

31

4.6.4 Optimal maintenance management for wind power systems with aspect on

reliability and cost BERTLING, Lina (Assistant Professor, Ph.D.) LANG, Andrea (PhD student) The goal for this project is to develop methods for optimal the maintenance management of wind power systems. The project will especially study how information from condition monitoring systems (CMS) can be used for this purpose. An optimal maintenance plan implies to prioritize the right tasks, for the right components, and the right time to reach a total least cost for maintenance. The research project is a result from a pre-study on RCM for wind power systems performed within the RCAM group (2005-2006). The project is closely related to an ongoing development project in Norway, run by EBL, with the aim to develop standards and procedures for using CMS for wind power systems. Currently the project involves one master thesis student, Michele Lucente, who is associated with NTNU in Trondheim. The master thesis project is on maintenance optimization of the gear box and the use of CMS. A PhD student has been recruited for the project, Andrea Lang, who started in December 2006. (Sponsored by Vindforsk) 4.6.5 Modelling of power equipment reliability with special reference to the impact of

maintenance BERTLING, Lina (Assistant Professor, Ph.D.) LINDQUIST, Tommie (Ph.D. student, Tech. Licentiate) Previous studies at the department show the importance of component reliability modelling and the difficulty in obtaining existing reliability data. The objective of this project is to develop equipment reliability models, which can be used for maintenance optimisation in power systems. The project is expected to give results on input data for equipment reliability/maintenance models, systematic characterization of fundamental failure mechanisms, equipment reliability models for key components in the power system and application study results. The project has, after focussing on the establishing of the relationship between the ageing of power system equipment and their failure rate, now moved to modelling the effect of maintenance on equipment reliability. A general reliability model including the effect of maintenance has been developed for disconnector contacts. This model will be enhanced by carrying out physical experiments and further statistical modelling.

32

Main activities during the year involves; a research visit at the University of Toronto (October 2005-March 2006). (Sponsored by the Elektra program) 4.6.6 Reliability and cost centred maintenance methods BERTLING, Lina (Assistant Professor, Ph.D.) NILSSON, Julia (PhD student) The goal for this project is to further develop the reliability-centred asset management method RCAM. The project shall include both reliability and cost considerations, and be focused on the introduction of the maintenance planning methods in different organizations. The focus for the application studies will be on production systems. Forsmark has been identified as a suitable place for an application study. During the autumn a research visit was made at Forsmark focusing on a review of the maintenance planning and spare optimization procedure. The project will also study life time cost analyses (LCC) as a part of RCAM. Within a master thesis project on wind power systems an LCC study was made to investigate the benefit of introducing condition monitoring systems for maintenance planning (Julia Nilsson). This model will be further developed both related to Forsmark and the PhD project within the RCAM group on wind power systems. On sight the project shall develop guidelines for how the cooperation with the different organizations and their suppliers should be handled, at purchases, including LCC and RCM. (Sponsored by the Competence Centre in Electrical Power Engineering at KTH, EKC2) 4.6.7 Reliability modelling and design for complex power systems with special focus on

the effects of introducing HVDC BERTLING, Lina (Assistant Professor, Ph.D.) SETRÉUS, Johan (PhD student) The goal for this project is the development and computer implementation of techniques, models and methods suitable for the assessment of reliability of complex power systems. The project shall investigate possible benefits and challenges introducing new techniques for the power system design with special focus on HVDC. The final goals are models and computer implementations that can be used for reliability assessment of complex power systems. Work within this project is performed in close collaboration with ABB Corporate Research, and Dr. Gabriel Olguin and also with STRI, Professor Math Bollen. Currently, there are three ongoing master theses project focusing on HVDC related to this research project.

33

During the autumn a research visit was been made with Sternö HVDC station owned by Swepolink arranged by Lars Marketeg (SvK). (Sponsored by the Competence Centre in Electrical Power Engineering at KTH, EKC2) 4.6.8 Risks in the electrical distribution systems with optimal maintenance management

and the effect of different regulatory models

BERTLING, Lina (Assistant Professor, Ph.D.) WALLNERSTRÖM, Carl Johan (PhD student) The goal for this project is to investigate the risks as effects of introduction of optimal maintenance and investment plans, e.g. RCAM plans, for electrical distribution systems. The project aims to investigate the long term effect expressed e.g. in availability, of maintenance management taking account new different circumstances for the electrical distribution systems e.g. new techniques, new laws and regulations, more private operators etc. Especially of interest is to take concern to the new law from 2006, with a compulsory annual analysis of risk and vulnerability for every distribution system operator (DSO). The project also considers the effect of the network assessment performance model (NPAM) and the long term affect of this model for the reliability of the system. The project is closely related to an ongoing research commitment for Svensk Energi that investigates the reliability of the network performance assessment model (NPAM) during 2004-2206. The studies shows on instabilities in the model and on how these could effect on the resulting output from the model i.e. on allowed tariffs. (Sponsored by the Riskprogram and EKC2)

5 Publications and reports 5.1 Ph.D. theses [1] Torbjörn Wass, Studies of high-temperature superconducting tapes and their applications in power systems, PhD Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2006

[2] Disala Uduwawala, A Comprehensive Study of Resistor-Loaded Planar Dipole Antennas for Ground Penetrating Radar Applications, PhD Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2006

[3] Yangjian Cai, Propagation of Some Coherent and Partially Coherent Laser Beams, PhD Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2006 5.2 Licentiate theses

34

[1] Nathaniel Taylor, Diagnostics of stator insulation by dielectric response and variable frequency partial discharge measurements, Licentiate Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2006

[2] Valentinas Dubickas, On-line time domain reflectometry diagnostics of medium voltage XLPE power cables, Licentiate Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2006 5.3 Master theses [1] Julia Nilsson, Maintenance management of wind power systems - Cost effect analysis of condition monitoring systems, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2006

[2] Hanif Tavakoli, An investigation of different reflectarray antenna elements, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2006

[3] Nima Farkhondeh Jahromi, Modeling the elongation of a water droplet inside an electrically stressed liquid, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2006

[4] Adib El-Sherif, Elektrisk influens p� fordon under kraftledning, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2006

[5] Johan Setréus, Development of a Simulation Module for the Reliability Computer Program RADPOW, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2006

[6] Johan Ribrant, Reliability performance and maintenance for wind power systems, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2006

[7] Thierry Pepy, Interface Management - Develop an Interface Management Tool within a large International Project, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2006

[8] Malin Calemark, Surface Charge Distribution of Corona Discharges studied with the Electro Optic Pockels Effect, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2006

[9] Shima Mousavi Gargari, Reliability assessment for complex power systems and the use of the NEPLAN tool, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2006 5.5 Books

35

[1] Lars Josefsson, Patrik Persson, Conformal Array Antenna Theory and DesignWiley-IEEE Press, 2006 5.6 Articles in journals [1] Johan Ribrant, Lina Bertling, "Survey of failures in wind power systems with focus on Swedish wind power plants during 1997-2005," IEEE transactions on energy conversion, (oct) 2006, Accepted for publication

[2] Julia Nilsson, Lina Bertling, "Maintenance management of wind power systems using Condition Monitoring Systems - Life Cycle Cost analysis for two case studies," IEEE transactions on energy conversion, (oct) 2006, Accepted for publication

[3] Torbjörn Wass, Sven Hörnfeldt, Stefan Waldemansson, "The magnetic circuit of a controllable reactor," IEEE Transactions on Magnetics, vol. 42, (no. 9,) pp. 2196-2200, (sep) 2006

[4] Lars Jonsson, Juerg Froehlich, Stephen Gustafson, Israel Michael Sigal, "Long Time Motion of NLS Solitary Waves in a Confining Potential," Annales Herni Poincare, vol. 7 pp. 621-660, (jan) 2006

[5] Patrik Persson, "Modeling Conformal Array Antennas of Various Shapes using UTD," ACES Journal, issue on Computation and Modeling Techniques for Phased Array Antennas, (nov) 2006

[6] Jian Qi Shen, Sailing He, "Dimension-sensitive optical responses of electromagnetically induced transparency vapor in a waveguide," PHYSICAL REVIEW A, vol. 74, (no. 063831,), (dec) 2006

[7] He J, Sailing He, "Slow propagation of electromagnetic waves in a dielectric slab waveguide with a left-handed material substrate," Microwave and Wireless Components Letters, IEEE, vol. 16 pp. 96- 98, (feb) 2006

[8] Yangjian Cai, Sailing He, "Propagation of various dark hollow beams in a turbulent atmosphere," OPTICS EXPRESS, vol. 14 pp. 1353-1367, (feb) 2006

[9] Yangjian Cai, Sailing He, "Average intensity and spreading of an elliptical Gaussian beam propagating in a turbulent atmosphere," Optics Letters, vol. 31 pp. 568-570, (mar) 2006

[10] Jian Qi Shen, Sailing He, "Backward waves and negative refractive indices in gyrotropic chiral media," JOURNAL OF PHYSICS A, vol. 39 pp. 457-466, (jan) 2006

[11] Song Jun, Zhu Ning, He Sailing, "Effects of surface roughness on the performance of an etched diffraction grating demultiplexer," JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A, vol. 23 pp. 646-650, (mar) 2006

[12] Jin Yi, He Jinlong, He Sailing, "Surface polaritons and slow propagation related to chiral media supporting backward waves," Physics Letters A, vol. 351 pp. 354-358, (mar) 2006

36

[13] J She, E Forsberg, X Y Ao, S L He, "High-efficiency polarization beam splitters based on a two-dimensional polymer photonic crystal," JOURNAL OF OPTICS A, vol. 8 pp. 345-349, (mar) 2006

[14] Yangjian Cai, Sailing He, "Propagation of hollow Gaussian beams through apertured paraxial optical systems," JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION, vol. 23 pp. 1410-1418, (jun) 2006

[15] Yangjian Cai, Sailing He, "Propagation of a partially coherent twisted anisotropic Gaussian Schell-model beam in a turbulent atmosphere," Applied Physics Letters, vol. 89, (no. 041117,), (jul) 2006

[16] Jun Song, Ning Zhu , Jian-Jun He, Sailing He, "Echelle grating demultiplexers with reduced return loss by using chirped diffraction order design," Photonics Technology Letters, IEEE, vol. 18 pp. 1506- 1508, (feb) 2006

[17] Jun Song, Ning Zhu, Sailing He, "Sidelobe suppression design of etched diffraction grating demultiplexers using optimized air trenches in front of each output waveguide,", vol. 23 pp. 2645-2649, (oct) 2006

[18] Yangjian Cai, Sailing He, "Partially coherent flattened Gaussian beam and its paraxial propagation properties," JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION, vol. 23 pp. 2623-2628, (oct) 2006

[19] Kuang J, Jin Y, He S, "An Open Wedge Cavity Based on the Negative Refraction of a Photonic Crystal," Microwave and Wireless Components Letters, IEEE, vol. 16 pp. 582-584, (nov) 2006

[20] Jian Qi Shen, Sailing He, "Backward waves and negative refractive indices in gyrotropic chiral media," JOURNAL OF PHYSICS A, vol. 39 pp. 457-466, (jan) 2006

[21] Gavita Mugala, Roland Eriksson, Per Pettersson, "Dependence of XLPE Insulated Power Cable Wave Propagation Characteristics on design Parameters," IEEE Transactions on Dielectrics and Electrical Insulation, (dec) 2006, Accepted for publication

[22] Ruslan Papazyan, Per Pettersson, David Pommerenke, "Wave Propagation on Power Cables with Special Regard to Metallic Screen Design,", (dec) 2006, Accepted for publication

[23] Sven Hörnfeldt, "Lifting force on metallic particles in GIS systems,", vol. 13, (no. 4,) pp. 838-841, (aug) 2006

[24] Gavita Mugala, Roland Eriksson, Per Pettersson, "Comparing two measuring techniques for frequency characterization of power cable materials," IEEE Transaction on Dielectrics and Electrical Insulation, vol. 13, (no. 4,) pp. 712-716, (aug) 2006

[25] David Ribbenfjärd, Göran Engdahl, "Modeling of Dynamic Hysteresis With Bergqvist," IEEE Transactions on Magnetics, vol. 42, (no. 10,) pp. 3135-3137, (oct) 2006

37

[26] Maria Ekelund, Hans Edin, Ulf Gedde, "Long-term performance of poly(vinyl chloride) cables. Part 1. Mechanical and electrical performance," Polymer degradation and stability, (feb) 2006, Accepted

[27] Steve Dejak, Lars Jonsson, "Long-Time Dynamics of Variable Coefficient mKdV Solitary Waves," Journal of Mathematical Physics, vol. 47, (no. 072703,) pp. 1--16, (apr) 2006

[28] Martin Norgren, "On the problem with intermodal dispersion when using multiconductor transmission lines as distributed sensors," Progress In Electromagnetic Research pp. 129-150, (jan) 2006, DOI: 10.2528/PIER05041401

[29] Disala Uduwawala, "Modeling and Investigation of Planar Parabolic Dipoles for GPR Applications: A Comparison with Bow-Tie Using FDTD," Journal of Electromagnetic Waves and Applications, (no. 2,) pp. 227-236, (feb) 2006, DOI: 10.1163/156939306775777224 5.5 Conference proceedings [1] Valentinas Dubickas, Hans Edin, "On-line time domain reflectometry measurements of temperature variations of an XLPE power cable," Conference on Electrical Insulation and Dielectric Phenomena, 2006

[2] Lina Bertling, Thomas Ackermann, Julia Nilsson, Johan Ribrant, "”Förstudie om tillförlitlighetsbaserat underhåll för vindkraftssystem – fokus på metoder för tillståndskontroll” (”Pre-study on reliability-centered maintenance for wind power systems with focus on condition monitoring systems”)," Elforsk report 06:39, 2006

[3] Ali Chowdhury, Lina Bertling, "Transmission Network Reconfiguration Using a Probabilistic Cost-Benefit Model," Proceedings of the 9th International Conference on Probabilistic Methods Applied to Power Systems (PMAPS), 2006

[4] Ali Chowdhury, Lina Bertling, "Distribution System In-Depth Causal Reliability Assessment," Proceedings of the 9th International Conference on Probabilistic Methods Applied to Power Systems (PMAPS), 2006

[5] A. A. Chowdhury, L. Bertling, D.E. Custer, "Determining Distribution Substation Transformer Optimal Loading Using a Reliability Cost-Benefit Approach," Proceedings of the 9th International Conference on Probabilistic Methods Applied to Power Systems (PMAPS), 2006

[6] Heggset J., Solvang E., Bertling L., Christensen J., Engen H., Bakken K.R, Pylvänäinen J., Hasseltröm J., "Failure models for network components as a basis for asset management," Proceedings of the Nordic Distribution and Asset Management Conference (NORDAC),, 2006

[7] Patrik Hilber, Lina Bertling, Bengt Hällgren, "Effects of Correlation Between Failures and Power Consumption on Customer Interruption Cost," Proceedings of the 9th

38

International Conference on Probabilistic Methods Applied to Power Systems (PMAPS), 2006

[8] Tommie Lindquist, "Reliability functions and optimal decisions using condition data for EDF primary pumps," 9th International Conference on Probabilistic Methods Applied to Power Systems (PMAPS), 2006

[9] B. Nyström, L. Austrin, N. Ankarbäck, E. Nilsson, "Fault Tree Analysis of an Aircraft Electric Power Supply System," Proceedings for PMAPS 2006, 2006

[10] J. E. Nowacki, U. Dar, L. Austrin, "AN ELECTRIC COOLING SYSTEM FOR AN UAV TOWARDS A BLEED-LESS TECHNOLOGY," Proc. ICAS 2006, 2006

[11] Martin Norgren, Takashi Takenaka, "Full Newton method for electromagnetic inverse scattering, utilizing explicit second order derivatives," Progress in Electromagnetic Theory Symposium 2006, 2006

[12] Johan Setréus, Lina Bertling, Shima Mousavi Gargari, "Simulation Method for Reliability Assessment of Electrical Distribution Systems," Proceedings of the Nordic Distribution and Asset Management Conference 2006 (NORDAC), 2006

[13] V. Volski, G. Vandenbosch, J. Yang, P.-S. Kildal, F. Vipiana, P. Pirinoli, G. Vecchi, P. de Vita, F. de Vita, A. Freni, P. Baccarelli, J. M. Rius, H. Espinosa, M. Mattes, A. Valero, Patrik Persson, Zvonimir Sipus, "Overview of the Software Integration Activities within ACE," 1st European Conference on Antennas and Propagation (EuCAP'2006), 2006

[14] Marko Bosiljevac, Patrik Persson, Zvonimir Sipus, "Hybrid Spectral Domain-UTD Method Applied to Conformal Antennas Analysis," 1st European Conference on Antennas and Propagation (EuCAP, 2006

[15] Patrik Persson, Lars Josefsson, "Antenna Pattern Synthesis of Singly Curved Conformal Array Antennas," Nordic Antenna Symposium (Antenn06), 2006

[16] Lars Josefsson, Patrik Persson, "On the Bandwidth of Omnidirectional Beamforming from Circular Arrays," Nordic Antenna Symposium (Antenn06), 2006

[17] Patrik Persson, Lars Josefsson, "Radiation and Mutual Coupling Characteristics of Antennas on Doubly Curved Surfaces," Nordic Antenna Symposium (Antenn06), 2006

[18] Zvonimir Sipus, Patrik Persson, Marko Bosiljevac, "Modeling Conformal Antennas using a Hybrid Spectral Domain-UTD Method," Nordic Antenna Symposium (Antenn06), 2006

[19] Anders Ellgardt, Patrik Persson, "Characteristics of a Broad-Band Wide-Scan Fragmented Aperture Phased Array Antenna," 1st European Conference on Antennas and Propagation (EuCAP'2006), 2006

39

[20] Roland Eriksson, Ruslan Papazyan, Gavita Mugala, "Localization of insulation degradation in medium voltage distribution cables," ICIIS 2006, University of Peradeniya, Srilanka, 8-11 August 2006, 2006

[21] Roland Eriksson, "Requirements on power supply reliability and its influence upon the design of Electricity distribution," Nordac 2006 August 21-22, 2006, 2006

[22] David Ribbenfjärd Göran Engdahl, "Modeling of Dynamic Hysteresis With Bergqvist," Proceedings of Intermag 2006, pp. 286, 2006

[23] David Ribbenfjärd, Göran Engdahl, "Time-domain transformer model in Dymola," Proceedings of IC-SCCE, 2006, Available on CD-ROM

[24] Patrik Persson, "Modeling Doubly Curved Conformal Array Antennas using UTD," The 22nd Int. review of progress in Applied Computational Electromagnetics (ACES 2006), 2006

[25] David Ribbenfjärd, Göran Engdahl, "Hysteresis Modeling Including Asymmetric Domain Rotation," Proceedings of CEFC 2006, pp. 283, 2006

[26] Lars Austrin, Mohsen Torabzadeh-Tari, Göran Engdahl, "A NEW HIGH POWER DENSITY GENERATION SYSTEM," Proc. ICAS 2006, 2006

[27] Mattias Oscarsson Göran Engdahl, "AN APPROACH TO OPTIMIZING THE COIL AND MAGNETIC CIRCUIT OF MAGNETOSTRICTIVE ACTUATORS," 2nd IC-SCCE, 2006

[28] Lars Austrin, Mohsen Torabzadeh-Tari, Anders Larsson, "ANALYSIS OF A FEASIBLE PULSED-POWER SUPPLY SYSTEM FOR AN UNMANNED AERIAL VEHICLE," Proc. ICAS 2006, 2006

[29] Mattias Oscarsson Göran Engdahl, "KEY NUMBERS IN DESIGN OF MAGNETOSTRICTIVE ACTUATORS AND GENERATORS," Actuator 2006, 2006

[30] Mohsen Torabzadeh-Tari, Lars Austrin, Sonja Tidblad-Lundmark, Göran Engdahl, "SIMULATION AND ANALYSIS OF A NEW HIGH POWER DENSITY GENERATOR," Proc. ICAS 2006, 2006

[31] Mohsen Torabzadeh-Tari, Lars Austrin, Martin Larsen, Göran Engdahl, "OPTIMIZATION AND CHARACTERISATION BY FINITE ELEMENT METHOD OF AN ELECTROMECHANICAL ACTAUTOR FOR MORE ELECTRIC AIRCRAFT APPLICATIONS," Proceedings for Actuator 2004 conference, 2006 5.6 Reports [1] Johan Setréus (2006), 'SwePol HVDC Link'

[2] Tommie Lindquist (2006), 'Diagnostic Techniques for Electric Insulation relevant to Dofascoïs 13.8kV PILC Cable System'

40

[3] Anders Ellgardt (2006), 'Electrical design of a wide-band wide-scan tapered notch element'

[4] Lina Bertling, Carl Johan Wallnerström (2006), 'Nätnyttomodellens tillförlitlighet med avseende på små förändringar i indata'

[5] Disala Uduwawala, Peter Fuks (2006), 'Ground penetrating radar measurements using a pair of resistor-loaded bow-tie antennas'

[6] Juerg Froehlich, Lars Jonsson, Enno Lenzmann (2006), 'Boson Stars as Solitary Waves', Accepted by Comm. Math. Phys 2007

[7] Martin Norgren, Takashi Takenaka (2006), 'Full Newton method for inverse transmission line problems utilizing explicit second order derivatives'

[8] M. Oscarsson G. Engdahl (2006), 'Mathematical plant of chosen actuator concept, part 1.'

[9] M. Oscarsson G. Engdahl (2006), 'D5.8 VIBEL design'

[10] Patrik Persson, Anders Ellgardt (2006), 'Förberedande analys för tillverkning av antennmodeller'

[11] Gavita Mugala, Roland Eriksson, Per Pettersson (2006), 'High Frequency Characteristics of Water-Treed Insulation Power Cables', Submitted to IEEE Transaction on Dielectrics and Electrical Insulation 5.8 Miscellaneous

[1] Bertling L, Karin Alvehag, Julia Nilsson, Johan Setreus (2006), 'Reliability Assessment of Electrical Power Systems - Project reports 2006'

[2] Martin Norgren (2006), 'Elektromagnetisk fältteori' [3] Göran Engdahl, Hans Edin, Martin Norgren, Staffan Rosander, Per Brunsell, Lars

Blomberg (2006), 'Electrotechnical Modelling' 6 Conferences, courses and visits January 19-20, 2006, Näsudden, Gotland. Study visit and research discussions at the Wind power farm owned by Vattenfall at Näsudden, within the RCAM research project on wind power. L. Bertling, J. Nilsson, J. Ribrant January 23-26, 2006, Newport Beach, California, USA. Annual Reliability and Maintainability Symposium (RAMS) 2006. T. Lindquist.

41

October 2005 – February 2006, INESC Porto, Portugal Research visit to INESC Porto, within a project on development of optimization methods. P. Hilber March 7, 2006 Eskilstuna, Sweden Energitinget L. Bertling, J. Setréus March 12-16, 2006, Miami, Florida, USA 22nd International Review of Progress in Applied Computational Electromagnetics (ACES 2006) P. Persson March 17, November 29-30, December 12, 15, 2006 Chalmers, Gothenburg Discussions on future co-operation with Chalmers/ Mathematical Sciences. L. Bertling April 3-8 April,2006, Dublin, Irland PEMD 2006 , 3rd IET International Conference on Power Electronics, Machines and Drives M. Torabzadeh-Tari, L. Austrin April 17-21, 2006, San Francisco, USAInvited talk in MRS (Material Research Society) 2006 Spring Meeting, “Some recent studies of negative index meta-materials and related structures” Sailing He April 30 May 8, 2006, Miami, USA CEFC 2006, The Twelfth Biennial IEEE Conference on Electromagnetic Field Computation D. Ribbenfjärd May 8-12, 2006, San Diego, California, USA INTERMAG 2006 Göran Engdahl May 12, 2006, IVA, Stockholm The first annual meeting for Power circle (Elkraftringen) L. Bertling, R Erikssonj 30 May – 1 June, 2006, Linköping, Sweden Attended Antenn06 P. Persson, Anders Ellgardt June 12-14, Stockholm, Sweden

42

PMAPS 2006 Lars Austrin, Göran Engdahl June 14-16, Bremen , Germany Actuator 2006, 10th International Conference on New Actuators Mattias Oscarsson, Mohsen Torabzadeh-Tari June 18-22, 2006, KTH, Stockholm, Sverige. Probabilistic Methods Applied to Power Systems (PMAPS), 2006. L. Bertling, R.Eriksson, H. Edin, A. Franzén, C. Forssén, P. Hilber, S. Karlsson, T. Lindquist, J. Nilsson, J. Setréus, C. J. Wallnerström June 19-21, 2006, Montréal, Canada The annual meeting of the IEEE Power Engineering Society (PES) General Meeting L. Bertling June 22-23, 2006, Toronto, Canada Research discussions and planning of a tutorial on Maintenance management for the next annual meeting of the IEEE PES General Meeting L. Bertling June 26, 2006, ABB, Ludvika Research discussions and study visit at ABBs transformer manufacture and laboratories at Ludvika. L. Bertling, G. Engdahl, A. Franzén, S. Karlsson, J. Krah June 26, 2006, ABB, Västerås Research discussion and presentation of master theses at ABB corporate research in Västerås. S. Gargari,,, J. Setréus July 5-8, Athens, Greece 2nd IC-SCCE, 2nd International Conference From Scientific Computing to Computational Engineering Mattias Oscarsson

August 2-5, 2006, Tokyo, Japan. PIERS 2006 Progress in Electromagnetic Theory Symposium. M. Norgren, J. Ramprecht. August 6-10, University of Nagasaki, Nagasaki, Japan. Visit with Prof. Takashi Takenaka at the Dep. of Electrical and Electronic Engineering. M. Norgren.

August 8-10, Peradeniya, Sri Lanka Invited lecture on insulation diagnostics at ICIIS 2006 R. Eriksson

43

August 13-17, 2006, San Diego, USASPIE (International Society for Optical Engineering) Annual Meeting,, Plenary talk in “Increasing the Density and Functionality of Photonic Integration with Nano-Waveguides and Nanostructures”, Sailing He August 21-22, 2006, Stockholm The Nordic Distribution and Asset Management Conference (NORDAC) L. Bertling, R. Eriksson, J. Setréus August 28, 2006, Olso, Norway The steering group meeting of the development project on Condition monitoring systems for wind power in Norway, jointly sponsored by the Vindforsk program. L. Bertling August 31- September 4, 2006, Paris, France Participated at the IEEE Region 8 Student Branch and GOLD Congrex, as representative from the IEEE Sweden Section L. Bertling Sept 3-7, 2006, Gwangju, Korea Invited tal in Asia-Pacific Optical Communications (APOC) 2006, “Highly Integrated Planar Lightwave Circuits Based On Si- and Plasmonic Nano-Waveguides”. Sailing He Sept 3-8, Hamburg, Germany ICAS 2006 Lars Austrin, Mohsen Torabzadeh-Tari September 14, 2006, ABB, Ludvika Research discussions at ABBs transformer manufacture at Ludvika. A. Franzén, S. Karlsson Sept 9-15, Banff, Canada BRIS Evolution of microscopic and macroscopic fields Talk: On the effective dynamics of the pseudo-relativistic Hartree equation Lars Jonsson Sept 25-28, St Maxime, France SAFT Defense Seminar 2006 Lars Austrin Oct. 15 - 18, Missouri, USA, Conference on Electrical Insulation and Dielectric Phenomena (CEIDP), Kansas City

44

Hans Edin, Valentinas Dubickas October 19, 2006 Stockholm, Sweden Elforsk on day conference on Risk methods presenting results from the OPAL project L. Bertling, C. J. Wallnerström October 26, 2006, Stockholm Elforskdagen A. Franzén, P. Hilber, T. Lindquist, J. Nilsson, J. Setréus, C. J. Wallnerström October 30, University of Toronto, Toronto, Canada One day meeting with maintenance researchers from the world L. Bertling October 31- November 3, Toronto, Canada International Maintenance Excellence Conference (IMEC) L. Bertling October 16-17, Ven. Meeting between electromagnetic theory groups from KTH, LTH, CTH & Växjö. A. Ellgardt, P. Fuks, L. Jonsson, M. Norgren, J. Ramprecht, S. Ström, G. Peterson, H. Xin November 6-10, 2006, Nice, France. The first European Conference on Antennas and Propagation (EuCAP 2006). A. Ellgardt, P. Persson. November 9, Quality Hotel Globe, Stockholm Nynas Insulating Oil Management seminar on the Inner environment of Transformers L. Bertling, A. Franzén, T. Lindquist, S. Karlsson November 13-14, EON, Malmö Research discussions and study visit with focus on failure reporting and maintenance of power transformer L. Bertling (only one day), A. Franzén November 15, SwePol HVDC Link, Karlshamn Study visit at the SwePol HVDC link between Sweden and Poland at Sternö in Karlshamn. R. Eriksson, S. Karlsson, R. Leelaruji, J. Setréus, O. Swaitti, L. Yu November 20-24, Forsmark, Östhammar Study visit at Forsmark Nuclear Power plant. Spare part optimization, Fault tree analysis and introduction to maintenance planning tool BICycle. J.Nilsson November 21, Ulfsunda Castle, Stockholm The autumn conference for the Faculty staff at KTH with focus on innovations

45

L. Bertling November 21, Quality Hotel Globe, Stockholm Slutkundsdagarna R.Eriksson, P. Hilber, J. Setréus, C. J. Wallnerström November 27-28, Brussel, Belgium Study trip and conference with KTH researcher and the president of KTH, on the EU research and the new 7th research program starting in 2006. L. Bertling December 1, Råcksta, Svenska Kraftnät Research discussions about the transformer life time modelling project A. Franzén, S. Karlsson

7 Seminars and lectures 7.1 Seminars and lectures at KTH February 15, 2006 Lecturers for STF Ingenjörsutbildning AB in a contract teaching course on “Power system evaluation techniques for distribution systems” and part three on “Technical and economical design and reliability modeling” L. Bertling, C. J. Wallnerström April 25, 2006 Seminar on Reliability-centered maintenance for wind power systems with focus on condition monitoring systems - results from two master theses projects and ongoing research (gathered round 30 persons in total from industry and academics) T. Ackermann, L. Bertling (co-ordinator), J. Nilsson, J. Ribrant June 5, 2006 Seminar on Reliability Evaluation of Electric Power Systems - results from two master theses projects and ongoing research (gathered round 30 persons in total from industry and academics) L. Bertling (co-ordinator), Shima Mousavi., G. Olguin (ABB corporate research), Johan Setréus. September 29, 2006 Seminar on Physical models for life time assessment of transformers – state-of-art overview and direction for research projects L. Bertling, D. Bormann, G. Engdahl, R. Eriksson, A. Franzén, S. Karlsson, D. Ribbenfjärd November 2, 2006

46

Docentföreläsning: Dynamics of a soliton in an external potential. –what is a soliton and how does it move? Lars Jonsson December 19, 2006 Lars Jonsson gave an informal seminar talk for the Laser Physics Group, KTH: “On the effective dynamics for some nonlinear evolution equations”

7.2 Seminars given outside KTH February 2, 2006 STEM/EMI, Eskilstuna, Sweden Seminar on ”Results from studies of the Network Performance Asset Model (NNM) at KTH for design and planning of electrical distribution systems” L. Bertling, C. J. Wallnerström. Feb. 27-Mar. 3, 2006, Lausanne, Switzerland Teacher at the ACE course “Analysis of Planar and Conformal Antennas” P. Persson March 7, 2006 Eskilstuna, Sweden Presentation at the Conference Energitinget on “Reliability of electrical distribution systems with respect to the network performance assessment model (NPAM)” L. Bertling March 8, 2006 Klara Strand Konferens, Sweden Invited lecturer at the one day education on the Network performance assessment model (NPAM) arranged by Svensk Energi L. Bertling, C. J. Wallnerström March 16, 2006 Gothenburg, Sweden Invited speaker at the seminar on Maintenance of electric power systems, arranged by UTEK, at the yearly conference on maintenance (Underhållsmässan) on Reliability-centred maintenance management”. L. Bertling April 25, Göteborg, Sverige Presentation More Electric Aircraft given on ”Elkraftdagen Chalmers University of Technology Lars Austrin May 2, 2006, Svenska kraftnät, Råcksta Invited speaker at the manager seminar with talk on “Maintenance management – using reliability based methods”. L. Bertling June 28-30, Paris, France

47

Presentation on Power Optimized Aircraft , TEOS 2006-12-19 Lars Austrin

August 2, 2006, Tokyo, Japan. PIERS 2006 Progress in Electromagnetic Theory Symposium. M. Norgren.

August 8-10, Peradeniya, Sri Lanka Invited lecture on insulation diagnostics at ICIIS 2006 R. Eriksson August 28, 2006, Olso, Norway Presentation of the new research project on Optimal Maintenance Management for Wind Power Systems with aspect to Reliability and Cost for SINTEF Energiforskning. L. Bertling October 10, 2006, Elforsk Presentation of the new research program on Maintenance Management within EKC2, for the steering group of the Development project on maintenance at Elforsk led by S. Jansson L. Bertling November 1, 2006, Toronto, Canada Invited presentation at the International Maintenance Excellence Conference (IMEC) L. Bertling November 9, 2006, Nice, France The first European Conference on Antennas and Propagation (EuCAP 2006). A. Ellgardt. November 9, 2006, Quality Hotel Globe, Stockholm Invited presentation at the Nynas Insulating Oil Management seminar on the Inner environment of Transformers L. Bertling, November 23, 2006, Modern museum, Stockholm Invited presentation at the seminar on Invite the whole world, arranged by the Stockholm Visitor Board L. Bertling December 12, Chalmers, Gothenburg Invited presentation at seminar on a morning with optimization at Chalmers/Mathematical Sciences L. Bertling

8 Other activities 8.1 National assignments

48

L. Austrin. Suppleant in Saab Aerosystems Technology Board. L. Bertling participated at the KTH Learning Lab course on Learning education part 2 (LU2) – dialogue seminar series, during January 2006- May 2006. L. Bertling participated at the KTH Executive course on Infrastructure changes, September 2005- January 2007. L. Bertling has participated in a research project on Women as a power resource in change and innovation processes at KTH, also involving Vattenfall and Volvo (2006-2007). L. Bertling.Member of the steering group of the trade union SACO at KTH, as a representative for the School of Electrical Engineering, during 2006-2007. L. Bertling. Mentor in a program for students at KTH with special, focus on supporting female PhD students (2006-2007). L. Bertling. Member of the steering group of IEEE Sweden Section, and has acted as secretary during 2006. L. Bertling. Project leader a research commitment from Svensk Energi (2005-2006) to evaluate the robustness of the network performance assessment model (NPAM). L. Bertling. Project leader for a research commitment from Elforsk (2005-2006) to identify problem areas and possible solutions for optimal maintenance management of wind power systems. The project resulted in a proposal for a new research project to Vindforsk, which was approved. L. Bertling. Expert to evaluate the Värmeforsk (Thermal Engineering Research Institute) project T5-515 about developments and trends of maintenance methods and to act as a member of the steering group (2005-2006). L. Bertling. Member of a steering group at Svensk Energi with the purpose of developing a manual for Risk and vulnerability of the electrical distribution systems in Sweden (2006) L. Bertling. Manager for the research program on Maintenance management of the Competence Centre in Electric Power engineering EKC2 with a yearly budget of around 6MSEK. G. Engdahl was assigned by the government to serve as technical specialist in patent trials until 2009-12-31. G.Engdahl. Opponent at the Ph.D. thesis defense of Oscar Danielsson, Ångströmlaboratoriet, Uppsala Universitet, Sweden

49

R. Eriksson. Expert for evaluation of applications for one adjunct professor position and one senior lecturer position in high voltage engineering at Chalmers University of Technology. R. Eriksson. MKember of the board of the School of electrical engineering, KTH R. Erikson. Member of the Swedish national committees of Cigré and Cired and the board of Elkraftringen. M. Norgren. Member of the evaluation committee at PhD defense of Sandy Sefi, Computer Science and Communications, KTH, Sweden. M. Norgren. Member of the evaluation committee at PhD defense of Christian Engström, Dep. of Electroscience, Lunds Tekniska Högskola, Sweden. M. Norgren. Member of the evaluation committee at PhD defense of Jon-Erik Dahlin, Div. of Fusion Plasma Physics, KTH, Sweden. 8.2 International assignments L. Bertling. Reviewer of the journals IEEE Transactions of Power Systems (3 papers), the Electric Power Systems Research (2 papers), the IET Generation, Transmission & Distribution (2 papers), and conference papers for the IEEE PES General Meeting 2006 and PMAPS2006. L. Bertling. Member of a working group within the Scandinavian research project OPAL that aims to develop a joint interruption reporting system for the electrical distribution operators (2005-2006). L Bertling. Member of the steering group for the Norwegian research project on reliability of wind power systems, run by SINTEF Energiforskning (2006-). L. Bertling. Member of the PMAPS International Society as chairman of the PMAPS2006 conference, and as a member of the International Technical Advisory Committee for PMAPS2006 and 2008. L. Bertling. Member in the Reliability Risk and Probability Applications Subcommittee of the IEEE Power Engineering Society, and is chairman of a task force on distribution systems, and is currently organizing a tutorial for the IEEE PES annual meeting in 2007. L. Bertling. Member of the Technical Advisory Committee of the 2007 IEEE PowerTech Conference. H. Edin. Reviever of IEEE transactions on Dielectrics and Electrical insulation. H.Edin. Member of NORKAB

50

R. Eriksson. Expert for evaluation for one professor position in high voltage engineering at NTNU, Trondheim. R. Eriksson. Reviewer of the journal Electric Power Systems Research and IEE Proceedings of Generation, Transmission & distribution. R.Eriksson Member of the IEEE Power Tech Conference steering committee. R.Eriksson. Member of the ICIIS Conference in Sri Lanka steering committee. Sailing He. General Co-chair for “International Symposium on Biophotonics, Nanophotonics, and Metamaterials” [October 16-18, 2006, Hangzhou, China] Sailing He. General Co-chair for OSA (Optical Society of America) Topical Conference on Nanophotonics [June 18-21, 2007 , Hangzhou, China]

Sailing He. Program Co-chair for the Asia Optical Fiber Communication & Optoelectronic Exposition & Conference (AOE) 2007 ( co-sponsored by IEEE LEOS and OSA; Shanghai, China, October 17-19,2007). Sailing He. Technical Program Committee for ECOC (European Conference on Optical Communication) Sailing He. Steering Committee for APOC (Asia-Pacific Optical Communications) from 2007 Sailing He. Scientific Advisory Board for the international journal "Metamaterials" (ISSN: 1873-1988) published by ELSEVIER.

Sailing He. Advisory Committee for the First International Congress on Advanced Electromagnetic Materials for Microwaves and Optics (Rome, Italy, 2007) Sailing He. INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION: Technical Program Committee for 2006 (Singapore) and Overseas Corresponding member for 2007 (Japan). Sailing He. Technical Program Committee for IEEE International Workshop on Antenna Technology: Small and Samrt Antennas, Metamaterials and Applications (iWAT2006, Singapore; iWAT2007, Cambridge, U.K.) Sailing He. Technical Program Committee for IEEE/LEOS International Conference on Optical MEMS and NanoPhotonics (Taiwan, 2007)

51

Sailing He. Reviewed over 20 papers in 2006 for international journals (like Physical Review Letters, IEEE/OSA Journal of Lightwave Technology, IEEE Photonics Technology Letters, Optics Letters, Applied Physics Letters, Optics Express). M. Norgren. Reviewer for Journal of Optics A: Pure and Applied Optics (1 paper) and IEEE Transactions on Antennas and Propagation (1 paper). P. Persson. Reviewer for IEEE Transactions Antennas and Propagation P. Persson. Co-organizer and co-chairman of the special session on “Conformal Antennas” at EuCAP 2006, Nice, France, 6-10 November 2006. P. Persson. Member of the scientific committee for the EMB07 conference, to be held in Lund, Sweden, October 18-19, 2007. P. Persson is an adjunct researcher in Chase to be established at Chalmers, a VINNOVA granted a 210 MSEK research program for 10 years, starting in 2007. KTH/ETK/P. P.Persson. Plans for giving courses based on the book on conformal antennas have been discussed. After a meeting with Birgit Jacobsson at CEI-Europe (www.cei.se) there will be a course in the spring of 2007 titled Advanced Array Antennas: Conformal Arrays and Digital Beamforming. Lecturer: L. Josefsson, P. Persson and H. Steyskal. The CEI-Europe course programs attract participants from a diversity of nations and professional backgrounds: research scientists (from both basic and application levels), practicing engineers and engineering managers, R&D specialists, patent officers, suppliers to high tech firms. 8.3 Mobility Sailing He is 50% engaged as research leader in Joint Research Centre of Photonics between Zhejiang University, China and KTH. The joint research includes Ph.D. students and Post Docs at both universities. Patrik Hilber spent the period October 2005 until March 2006 at the research institute INESC in Porto, Portugal. Lars Jonsson were on research leave until October 2006 at the Department of Theoretical Physics of ETH, Zurich, Switzerland. Tommie Lindquist spent the period October 2005 until March 2006 at the University of Toronto, Canada. Martin Norgren made a research visit to Department of Electrical and Electronics Engineering at the University of Nagasaki, Japan.

52

In a Sida project for competence building Disala Udawawala was a sandwich Ph.D. student from University of Peradeniya, Sri Lanka. Dr Dierk Borrmann from ABB Corporate Research and Dr. Per Pettersson from Vattenfall Research were engaged in the activities of the department during the year: